HadISST1 - Global sea ice and Sea Surface Temperature analyses
Global SST fields were created using a variety of techniques including Reduced Space Optimal Interpolation (RSOI). Sea ice concentration fields from different sources were analysed to make them as consistent as possible through time. Some care should be taken when using the sea-ice concentration data, particularly in the Southern Hemisphere where there is no realistic interannual variability in sea ice prior to 1973. The HadISST1 data set has been shown to be an improvement upon (and has superseded) the GISST data set.